WBBSE Solutions For Class 7 Geography Chapter 1 Earths Revolution Topic A Revolution Of The Earth

Chapter 1 Earths Revolution Synopsis

• Any two bodies in the universe attract each other with a force. This force is known as the gravitational force.
• The imaginary line that joins the North and the South Poles and passes through the center of the Earth is known as the Earth’s axis. The Earth takes nearly 24 hours to rotate once around its axis.
• The extreme northern and southern ends of the Earth’s axis are known as the Poles.
• If an object is thrown upwards at a velocity of 11.2.km/sec, it will go past the gravitational force of the Earth and will start revolving around the Earth. This velocity is known as the escape velocity of the object in the case of the Earth.
• The elliptical path along which the Earth. revolves around the Sun is called its orbit.
• The imaginary plane on which the orbit of the Earth is situated is known as the orbital plane of the Earth.
• Aphelion is the position when the Earth is farthest from the Sun. The Earth reaches its Aphelion position on 4 July when it is 15 crore 20 lakh km away from the Sun.
• Perihelion is the position when the Earth is nearest to the Sun. It occurs on 3 January every year when the distance between the Sun and the Earth is 14 crore 70 lakh km.

WBBSE Solutions For Class 7 Geography

• The Earth’s satellite, Moon takes 27 1/3 days to revolve around the Earth. This time period is called a lunar month.
• The Earth orbits the Sun once in about 365 days. This time period is known as a solar year.
• Leap year is a special kind of calendar year which contains 366 days, having 29 days in the month of February. The actual time taken by the Earth to complete one revolution is 365 days 5 hours 48 minutes and 46 seconds.
• This is rounded off as 365 days for the ease of calculation. But to balance this extra 6 hours is added to the month of February (6×4-24 hours or 1 day) after every four years.
• Due to the Earth’s rotation, it seems that the Sun rises in the east and sets in the west. The Sun’s daily movement across the sky from the east to the west is known as the apparent diurnal movement of the Sun.
• The sun rays are incident vertically on the Tropics and Equator during different times of the year. Thus, the Sun seems to march between the Tropic of Cancer (23½°N) and the Tropic of Capricorn (23½°S). This apparent movement is known as the apparent annual movement of the Sun or the Solar Ecliptic.
• For six months from 22 December to 21 June, the Sun moves towards the northern direction. This movement of the Sun is known as the apparent movement of the Sun towards the north.
• For six months from 21 June to 22 December, the Sun gradually moves in a southerly direction. This movement of the Sun is known as the apparent movement of the Sun towards the south.
• On 21 June, the sun rays are incident on the Tropic of Cancer at 90°. This day is known as Summer Solstice. This is the longest day and shortest night in the northern hemisphere. Conversely, this day is the shortest day and longest night in the southern hemisphere.
• On 22 December, the Sun comes overhead on the Tropic of Capricorn. This day is known as the Winter Solstice. This event is characterized by the shortest day and longest night is the northern hemisphere and the longest day and shortest night is the southern hemisphere.
• On 21 March each year, the Sun remains overhead on the Equator. This day is known as the Vernal Equinox. Since this day marks the beginning of spring in the northern hemisphere is also known as the Spring Equinox.
• The Sun again remains overhead on the Equator on the 23 September every year. This day is called the Autumnal Equinox since it marks the beginning of autumn in the northern hemisphere. There is 12 hours of the day and 12 hours of night everywhere on Earth on the equinoxes.
• In regions north of the Arctic Circle (places of countries like Denmark, Canada, Norway, Sweden, Iceland, etc) the Sun is visible at the horizon even at night according to local time from the months of March-July. This is known as the midnight Sun.
• The Sun can be clearly seen at night according to local time from May to July in the port of Hammerfest to the north of Norway. That is why Norway is called the Land of the Midnight Sun.

Chapter 1 Topic A Revolution Of The Earth Analytical Type Questions

Question 1. What is an ellipse? How different is it from a circle?
Answer:

Ellipse:

An ellipse has two axes, the major axis AB and the minor axis CD (see figure), which intersect at the center O. In an ellipse, there are two foci, F and F1, equidistant from the center ‘O’.

1. Here, AB And CD = Two axies of equal length
2. O = Centre

 

1. Here, AB = Major Axis CD Minor Axis
2. O = Centre
3. F and F1 = Two Foci

Difference between circle and ellipse:

The difference noticed between a circle and an ellipse from the figure are-

WBBSE Class 7 Earth’s Revolution

Short Analytical Type Questions

Question 1. Explain the Law of Gravitation as per Newton. Does this work in the outer space too?
Answer:

Law of Gravitation as per Newton:

Newton’s Law of Gravitation states that any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

This law was discovered by Newton in the year 1867. Yes, this Law of Gravity is applicable in the outer space too.

Question 2. Write a brief note on the Milky Way.
Answer:

Milky Way:

The Milky Way is the galaxy that contains our solar system. Its name ‘milky’ is derived from its appearance as a dim glowing band arching across the night sky in which individual stars cannot be distinguished.

The diameter of the Milky Way is about 0.1 million light-years i.e. light would take 0.1 million years to travel from one end to the other.

Question 3. What are the distinct characteristics of the Earth as it revolves around the Sun?
Answer:

Characteristics of the Earth as it revolves around the Sun:

As the Earth revolves around the Sun, the following distinct characteristics are observed-

1. Elliptical orbit: The Earth moves around the Sun in a fixed elliptical path known as the Earth’s orbit.

2. Counter-clockwise movement: The Earth moves around the Sun along an elliptical path in an anti-clockwise direction.

3. Speed: The Earth revolves around the Sun at a speed of 30 km per second.

Question 4. What do you mean by the revolution of the Earth?
Answer:

Revolution of the Earth:

The Earth’s revolution refers to its movement around the Sun along a defined elliptical orbit. It takes 365 days, 5 hours, 48 minutes and 46 seconds or 1 year for the Earth to complete one revolution around the Sun.

The speed of the revolution of the Earth is 107000 km/h or 30 km/second.

Question 5. What are the types of the Earth’s motion?
Answer:

The Earth does not remain static in space, it is always in motion.

The Earth’s movement is of two types-

1. Rotation,
2. Revolution.

1. Rotation:

Rotation is the motion of the Earth on its own axis. It takes 24 hours for the Earth to complete one rotation and causing the occurrence of day and night.

2. Revolution:

Revolution is the motion of the Earth around the Sun. It takes 365 days, 5 hours, 48 minutes, and 46 seconds to complete one revolution.

Question 6. What is escape velocity? If an object is thrown upwards at a velocity of 11.2 km per second, it does not fall back to the surface. Why?
Answer:

Escape velocity:

Escape velocity is the velocity at which an object needs to travel to break free from a planet’s gravitational field and leave it without further propulsion.

The escape velocity of an object from the Earth’s surface is 11.2 km per second. However small or big an object may be, the escape velocity is the same for all i.e. it does not depend on the mass of the object.

Question 7. Discuss the features of the Earth’s orbit.
Answer:

Features of the Earth’s orbit:

The path along which the Earth revolves around the Sun is called its orbit. Its features are as follows-

1. It is elliptical in shape.
2. Its circumference is about 940 million km.
3. The Sun lies at the focus of the orbit.
4. The plane on which the orbit lies is called the orbital plane.
5. The speed at which the Earth revolves around the Sun along its orbit is approximately 30 km/s.
6. The Earth revolves around the Sun along this path from west to east in 365 days 5 hours 48 minutes 46 seconds.

Understanding Earth’s Revolution and Seasons

Question 8. What are the three universal ways of determining time?
Answer:

Three ways of determining time are as the time lag. Therefore, in every 4 years follows-

1. On the basis of rotation:

Every 24 hours gives us a new day and a night. We consider 24 hours to be 1 day and break it into 24 parts.

2. On the basis of revolution:

The Earth takes 365 days to complete 1 revolution around the Sun. Considering 365 days to be 1 year we can determine time.

3. On the basis of lunar month:

The Moon, the only natural satellite of the Earth takes about 28 days (27 days 3 hours) to complete one revolution around the Earth. These 28 days are considered to be 1 month, though we have months of 30 and 31 days.

Question 9. Define leap year. or, Why does the month of February have 29 days after every 4 years? or, What is the reason behind the addition of a day in the calendar in every 4 years?
Answer:

Leap year:

The period of time taken by the Earth to complete one revolution around the Sun (365 days, 5 hours, 48 minutes, and 46 seconds) is known as a solar year.

For ease in calculation, this time is taken as 365 days and 6 hours (5 hours, 48 minutes, 46 seconds).

The extra 6 hours of each year is added after every 4 years to the month of February (6 x 4 = 24 hours or 1 day) to adjust February has 29 days. This year with 366 days is known as a leap year.

Question 10. Identify the leap years- 2004, 2000, 2012, 1900, 2013, 2100.
Answer:

Year	Leap Year
	Yes	No
2004	Yes	–
2000	Yes	–
2012	Yes	–
1900	–	Yes
2013	–	Yes
2100	–	Yes

 

Question 11. Differentiate between the orbit and orbital plane of the Earth.
Answer:

The differences between the orbit and the orbital plane of the Earth are-

 

Question 12. Why is the heat produced by vertical sun rays more intense than that of oblique sunrays?
Answer:

The reasons for which the heat produced by vertical sun rays is more are as follows-

1. In comparison to the vertical sun rays, oblique sunrays travel a longer distance through the atmosphere and thus, produce
   less heat.
2. Since the oblique rays travel a longer distance through the atmosphere, part of it gets absorbed by the surface of the water vapour droplets and minute dust particles in the atmosphere. Since the vertical rays travel a shorter distance lesser part of it gets absorbed by the atmospheric components.
3. The vertical sunrays are concentrated on a smaller portion of the Earth’s surface and so the heat produced is much more than that by the oblique ones.

Question 13. What is the reason behind the seasonal changes on the Earth’s surface?
Answer:

The Earth’s seasons are not caused by the distance from the Sun but the tilt in the Earth’s axis.

Due to this tilt different parts of the globe are oriented toward the Sun at different times of the year resulting in differential heating of the land surface. Therefore, we experience seasonal changes.

Question 14. During winter, in the northern hemisphere, the Sun appears to be bigger in size. Why?
Answer:

The Sun is positioned at the center of the elliptical orbit of the Earth. The Earth-Sun distance is not constant and varies throughout the year.

On 3 January when it is winter in the northern hemisphere, the Earth reaches a point nearest to the Sun (Sun-Earth distance is 14 crore 70 lakh km). Therefore the Sun appears bigger in size when seen from the Earth.

Question 15. What is the role of the daily motion of the Earth in determining time in hours, minutes, and seconds?
Answer:

The geoid-shaped Earth takes 24 hours to complete one full rotation on its own axis from west to east. Every 1° rotation takes 4 mins (i.e. 360° x 4 minutes = 24 hours).

Thus we divide each day into 24 parts and consider each part to be an hour. Further, 1 hour is divided into 60 minutes and 1 minute is divided into 60 seconds. In this manner, we can determine the time at a place in hours, minutes, and seconds.

Chapter 1 Topic A Revolution Of The Earth Short Answer Type Questions

Question 1. What happens if you drop a ball from your hand?
Answer:

If we drop a ball from our hand, it will fall on the ground. This is because the Earth attracts every object towards its center.

Thus, we do not fall off from the surface of the Earth and stay on it. This attraction is known as the gravitational force.

Question 2. What is the Earth attracted to?
Answer:

Earth attracted to:

According to the law of gravity, every object in this universe attracts other objects. Likewise, the Earth also attracts any object closer or farther away from it and also gets attracted to any such.

The heaviest object closest to the Earth is the Sun. Compared to the Earth the Sun is 13 lakh times bigger and thus the Earth is always attracted to it.

Question 3. If we drop a ball from our hand, it will fall on the ground. The Earth is like a heavy ball and also has chance of falling. In which direction and why will it fall? Or, The Earth is also a heavy sphere. Suppose the Earth also falls like a ball, what will happen to us?
Answer:

The Earth is constantly acted upon by the Sun’s gravity. If at all the Earth’s motion stops, then it will fall on the Sun’s surface.

Short MCQs on Earth’s Movement Around the Sun

Question 4. What problems would we have had faced in the absence of the gravitational force?
Answer:

Gravitational force is responsible for the presence of an atmosphere, water, humans, birds animals, etc. on the surface of the Earth.

In the absence of gravitational force, these would not have had existed and the Earth would have been a lifeless planet.

Question 5. An apple falls on the Earth’s surface from a tree. Both the apple and the Earth have the gravitational force of their own by which they attract each other. Then why does the apple fall down on the Earth’s surface and not the other way around?
Answer:

Objects with more mass have more gravity.

As the mass of the Earth is many times greater than the mass of the apple, the force acting on the apple is far stronger than the force acting on the Earth. So the apple falls on the Earth and not the other way round.

Question 6. How does the Earth move smoothly around the Sun?
Answer:

The Earth revolves around the Sun along a fixed elliptical path. An object requires a centripetal force to revolve around the Sun. This centripetal force is provided by the Sun itself, helping in the swift movement of the Earth along its path.

Question 7. If you place a small piece of paper on a ball and let it go after rotating it, the paper would fall off. Similarly, we reside on the Earth’s surface but don’t fall off. Why?
Answer:

In the given example we saw that the ball did not have any gravitational force of its own due to which the piece of paper fell off from its surface.

Our Earth has its own gravitational force that always attracts us downwards and hence, we do not fall off from its surface.

Question 8. What do you mean by rotation?
Answer:

Rotation:

The spinning of the Earth on its own axis is termed as Earth’s rotation. The average rotation period of the Earth is 23 hours 56 minutes 4 seconds i.e. 24 hours.

Question 9. Why is the Earth’s revolution also called the annual motion of the Earth?
Answer:

The Earth takes 365 days, 5 hours, 48 minutes, and 46 seconds to complete one revolution around the Sun. Since 365 days is taken to be 1 year the movement is also known as the annual motion of the Earth.

Question 10. What is the orbit of the Earth?
Answer:

Orbit of the Earth:

The elliptical path along which the Earth revolves around the Sun is termed as the Earth’s orbit. The circumference of the orbit is about 940 million km.

The Sun is positioned at the center or focus of the elliptical orbit.

Question 11. State Kepler’s first law.
Answer:

Kepler’s first law:

Kepler’s first law says, “Each planet revolves around the Sun in an elliptical orbit with the Sun at the focus of the ellipse.”

Question 12. What is Earth’s orbital plane?
Answer:

Earth’s orbital plane:

The imaginary plane on which the orbit of the Earth is situated is known as the orbital plane of the Earth. This two-dimensional plane is elliptic in shape and prevents celestial bodies from bumping into each other.

The center of the Sun and the center of the Earth are on the same orbital plane.

Question 13. What is Perihelion?
Answer:

Perihelion:

Perihelion is the position when the Earth is nearest to the Sun. It occurs on 3 January every year and the Sun-Earth distance at this point is about 14 crore 70 lakh km.

The word Perihelion is derived from the Greek words ‘peri’ meaning near and ‘helios’ meaning the Greek God of the Sun.

Question 14. What is Aphelion?
Answer:

Aphelion:

Aphelion is the position when the Earth is farthest from the Sun. The Earth reaches its Aphelion position when the northern hemisphere July when it is about 15 crore 20 lakh km away from the Sun.

The word Aphelion is derived from the Greek words ‘apo’ meaning away or, apart, and ‘helios’ meaning the Greek God of the Sun.

Question 15. What is a lunar month?
Answer:

Lunar month:

The Earth’s satellite Moon revolves around the Earth in about 27% of days or 28 days (approx). This time period is called a lunar month.

Question 16. What is a solar day?
Answer:

Solar day

Solar day refers to th:e interval between two successive returns of the Sun to the local meridian. The length of a solar day varies throughout the year.

Question 17. How will you identify a year as a leap year?
Answer:

A year can be termed a leap year only if it is completely divisible by 4. In the case of millennium years like 1600, 2000, 2400, and so on, if it is divisible by 400 then it is a leap year.

Common Questions on Effects of Earth’s Tilt

Question 18. What do you know about the Earth’s axis?
Answer:

Earth’s axis:

The imaginary line that joins the North and the South Poles and passes that through the center of the Earth is known as the Earth’s axis. It is tilted, making an angle of 66½° with the orbital plane.

Question 19. What is the position of the Earth’s axis as it moves around the Sun?
Answer:

As the Earth moves around the Sun, its axis makes an angle of 66½° with the orbital plane.

This tilt in the axis is responsible for the orientation of the North Pole towards the Pole Star and the South Pole towards Hadley’s Octant. The angular tilt of the Earth’s axis is fixed irrespective of its position.

Question 20. One bucket of water warms up within half an hour if it is placed in the Sun at noon. When do you think we get more heat during day time?
At the time of sunrise
At noon when the Sun is overhead During sunset
At night after sunset
Answer:

At noon when the Sun is overhead.

Question 21. What is escape velocity?
Answer:

Escape Velocity:

If an object is thrown upwards at a velocity of 11.2 km/sec, it will go past the gravitational force of the Earth and will start revolving around the Earth. This velocity is known as the escape velocity of the object in the case of the Earth.

Question 22. Why is the axis of the Earth tilted? Or, Why does the axis of the Earth make an angle of 66% with its orbit?
Answer:

Scientists believe that during the formation of the Earth due to collision with several extraterrestrial elements the axis of the Earth got inclined at an angle of 662°.

Question 23. On 3 January, the Sun-Earth distance is minimum (14 crores 70 lakh km) as a result of which we should feel warmer but we normally feel cold. Why?
Answer:

On 3 January, the southern hemisphere is tilted towards the Sun while the northern. hemisphere is tilted away from it. Due to this, the Sun’s rays fall vertically over the southern hemisphere and obliquely over the northern hemisphere and hence, we feel cold.

Chapter 1 Topic A Revolution Of The Earth Multiple Choice Questions Choose The Correct Option

Question 1. The Earth takes to complete one revolution around the Sun.

1. 24 hours
2. 365 days 5 hours 48 minutes and 46 seconds
3. 366 days

Answer: 2. 365 days 5 hours 48 minutes and 46 seconds

Question 2. The movement of the Earth around the Sun is known as-

1. Rotation
2. Revolution
3. Solar day

Answer: 2. Revolution

Question 3. The average rotation period of the Earth is-

1. 23 hours
2. 23 hours 56 minutes 4 seconds
3. 24 hours 56 minutes 4 seconds

Answer: 2. 23 hours 56 minutes 4 seconds

Question 4. The Earth revolves around the Sun at a speed of about-

1. 11.2 km per second
2. 30 km per second
3. 25 km per second

Answer: 2. 30 km per second

Practice MCQs on Day and Night Cycle

Question 5. The Moon completes one revolution around the Earth in-

1. 27 1/3 days
2. 29 days
3. 31 days

Answer: 1. 27 1/3 days

Question 6. To complete one revolution around the Sun the Earth rotates-

1. 365 times
2. 24 times
3. 366 times

Answer: 1. 365 times

Question 7. The shape of the Earth’s orbit is-

1. Circular
2. Elliptical
3. Square

Answer: 2. Elliptical

Question 8. Escape velocity from the surface of the Earth is-

1. 11.2 km per second
2. 12.2 km per second
3. 13.2 km per second

Answer: 1. 11.2 km per second

Question 9. During the Earth’s revolution, the Sun-Earth distance is maximum on-

1. 3 January
2. 4 July
3. 21 June

Answer: 2. 4 July

Question 10. The maximum distance of the Earth from the Sun is-

1. 14 crore 70 lakh km
2. 15 crore km
3. 15 crore 20 lakh km

Answer: 3. 15 crore 20 lakh km

Question 11. At Perihelion, the Earth-Sun distance is-

1. 14 crore 70 lakh km
2. 15 crore 20 lakh km
3. 10 crore 13 lakh km

Answer: 1. 14 crores 70 lakh km

Question 12. The Earth is at Aphelion position on-

1. 4 July
2. 3 January
3. 4 June

Answer: 1. 4 July

Question 13. At Aphelion the Earth-Sun distance is-

1. 14 crore 75 lakh km
2. 15 crore 20 lakh km
3. 15 crore km

Answer: 2. 15 crore 20 lakh km

Question 14. The Earth receives one part of solar radiation daily at the upper atmosphere.

1. One Billionth
2. Two Billionth
3. Three Billionth

Answer: 2. Two Billionth

Question 15. The point in the Earth’s orbit where it is nearest to the Sun is known as-

1. Perihelion
2. Aphelion
3. Equinox

Answer: 1. Perihelion

Question 16. The point in the Earth’s orbit where it is farthest from the Sun is known as-

1. Aphelion
2. Perihelion
3. Equinox

Answer: 1. Aphelion

Question 17. Throughout the year the Sun’s rays fall vertically over the-

1. Equatorial region
2. Polar region
3. Desert region

Answer: 1. Equatorial region

Question 18. As we move from the Equator towards the Poles, the speed of rotation of the Earth-

1. Increases
2. Decreases
3. Remains the same

Answer: 2. Decreases

Question 19. The shadow of a stick is the shortest at-

1. 6 a.m.
2. 12 noon
3. 4 p.m.

Answer: 2. 12 noon

Question 20. The shadow of a stick is longest at-

1. 6 a.m.
2. 12 noon
3. 2 p.m.

Answer: 1. 6 a.m.

Question 21. 1 day is equal to-

1. 1440 minutes
2. 60 minutes
3. 3600 minutes

Answer: 1. 1440 minutes

Question 22. A leap year has-

1. 365 days
2. 366 days
3. 367 days

Answer: 2. 366 days

Question 23. In a leap year, February has-

1. 28 days
2. 31 days
3. 29 days

Answer: 3. 29 days

Question 24. Leap years (except the century years) are divisible by-

1. 4
2. 8
3. 3

Answer: 1. 4

Question 25. The idea of a leap year was first put forward by the-

1. Egyptians
2. Greeks
3. Indians

Answer: 1. Egyptians

Question 26. was a leap year.

1. 2004
2. 2006
3. 2010

Answer: 1. 2004

Question 27. The axis of the Earth is inclined to its orbital plane at an angle of-

1. 23½°
2. 65½°
3. 66½°

Answer: 3. 66½°

Question 28. The tilt of the Earth, causes-

1. Day and night
2. Seasons
3. High and low tides

Answer: 2. Seasons

Question 29. Northern Hemisphere experiences-

1. Summer
2. Spring
3. Winter
4. Autumn

Answer: 3. Winter

Chapter 1 Topic A Revolution Of The Earth Very Short Answer Type Questions Fill In The Blanks

Question 1. The force of the Earth that holds us onto its surface is called _______.
Answer: Gravitational force

Question 2. The Sun is _______ lakh times bigger than the Earth.
Answer: 13

Question 3. The Sun is at the _______ of the solar system.
Answer: center

Question 4. ‘The Earth revolves around the Sun’-this idea was first put forward by _______.
Answer: Kepler

Question 5. Earth’s orbital path is _______.
Answer: Elliptical

Question 6. The idea of a heliocentric universe was first put forward by _______.
Answer: Copernicus

Question 7. The Theory of Planetary Motion was first put forward by famous scientist _______.
Answer: Kepler

Question 8. _______ is a result of the Earth’s rotation.
Answer: Day and night

Question 9. Smaller objects that move in an orbit around a larger object obey Newton’s Law of _______.
Answer: Gravitation

Question 10. In the month of _______ the Sun comes closest to the Earth.
Answer: January

Question 11. The duration of the solar year is _______
Answer: 365 days 5 hours 48 minutes 46 seconds

Question 12. The solar day is computed by _______ of the Earth.
Answer: Rotational

Question 13. The Sun takes _______ minutes to apparently cross one degree of longitude.
Answer: 4

Question 14. The year with 366 days is a _______.
Answer: Leap year

Question 15. During winter, in the northern hemisphere, the Sun appears to be slightly _______ in size.
Answer: Larger

Question 16. In the northern hemisphere, the Sun appears to be slightly smaller in size during _______.
Answer: Summer

Question 17. The Earth’s axis oriented in the direction of the Pole Star makes an angle of _______ with the orbital plane.
Answer: 662°

Question 18. The position of the North Pole is determined by the position of the _______.
Answer: Pole Star

Question 19. The Pole Star is observed in the _______ part of the sky in Kolkata.
Answer: Northern

Write True or False

Question 1. The Egyptians first applied the concept of leap year.
Answer: True

Question 2. The Earth’s orbital path is circular in shape.
Answer: False

Question 3. During the revolution, the Earth’s axis remains tilted at an angle of 652°.
Answer: False

Question 4. At Aphelion, the Sun-Earth distance is minimum.
Answer: False

Question 5. At Perihelion, the Sun-Earth distance is maximum.
Answer: False

Question 6. A year with 365 days, 5 hours, 48 minutes, and 46 seconds is considered to be a leap year.
Answer: False

Question 7. Escape velocity from the surface of the Earth is 11.7 km per hour.
Answer: False

Question 8. The year 2008 was a leap year.
Answer: True

Question 9. In the northern hemisphere during summer, the Sun appears to be smaller.
Answer: True

Find The Relation

Question 1. Speed of revolution: 30 km/sec:: Escape velocity:_________.
Answer: 11.2 km/sec

Question 2. Aphelion : _________:: Perihelion: 3 January.
Answer: 4th July

Question 3. Aphelion: 15 crore 20 lakh km:: Perihelion: _________.
Answer: 14 crores 70 lakh km

Question 4. Near to the Sun : _________:: Far away from the Sun: July.
Answer: January

Question 5. Lunar month: 27% days:: Solar year: _________.
Answer: 365 days

Chapter 1 Topic A Revolution Of The Earth Match The Columns

1.

Answer: 1. D, 2. A, 3. C, 4. B

2.

Answer: 1. B, 2. C, 3. A, 4. D

3.

Answer: 1. B, 2. A, 3. D, 4. C

4.

Answer: 1. B, 2. A, 3. D, 4. C

Answer In One Or Two Words

Question 1. Name the galaxy which contains the Sun and the entire solar system.
Answer: Milky Way.

Question 2. Where is the Sun located in the solar system?
Answer: Centre.

Question 3 What is the diurnal motion of the Earth on its own axis called?
Answer: Rotation.

Question 4 What is the name for the Earth’s movement around the Sun in 365 days?
Answer: Earth’s revolution.

Question 5. What is the term for the velocity at which an object thrown upwards from the Earth manages to escape the gravitational force of the Earth?
Answer: Escape velocity.

Question 6. What is the elliptical path on which the Earth moves around the Sun called?
Answer: Orbit.

Question 7. What is the line imagined to join the Poles of the Earth known as?
Answer: Earth’s axis.

Question 8. What is the name of the position attained on 3 January at which the Sun-Earth distance is minimum?
Answer: Perihelion.

Question 9. What is the name of the position attained on 4 July at which the Sun-Earth distance is maximum?
Answer: Aphelion.

Question 10 What is the period of 28 days during which the Moon completes one revolution around the Earth called?
Answer: Lunar month.

Question 11 What is a year that is exactly divisible by four called?
Answer: Leap year.

Question 12 What is the year with 366 days and with 29 days in February called?
Answer: Leap Year.

Important Definitions Related to Earth’s Revolution

Question 13. Mention the angle at which the Earth’s axis is tilted with respect to the orbital plane.
Answer: 66½°.

Question 14. Where on Earth are days and nights equal?
Answer: Equator.

Question 15. Name the planet whose axial line and orbital path are parallel to each other.
Answer: Uranus.

Question 16. Name the planet whose axis is perpendicular to the orbital plane.
Answer: Jupiter.